This invention relates to the field of guide wires for advancing intraluminal devices such as stent delivery catheters, balloon dilatation catheters, atherectomy catheters and the like within body lumens.
In a typical percutaneous procedure, a guiding catheter having a preformed distal tip is percutaneously introduced into a patient""s peripheral artery, e.g. femoral or brachial artery, by means of a conventional Seldinger technique and advanced therein until the distal tip of the guiding catheter is seated in the ostium of the desired coronary artery. There are two basic techniques for advancing a guide wire into the desired location within the patient""s coronary anatomy, the first is a pre-load technique which is used primarily for over-the-wire (OTW) devices and the bare wire technique which is used primarily for rail type systems.
With the pre-load technique, a guide wire is positioned within an inner lumen of an OTW device such as a dilatation catheter or stent delivery catheter with the distal tip of the guide wire just proximal to the distal tip of the catheter and then both are advanced through the guiding catheter to the distal end thereof. The guide wire is first advanced out of the distal end of the guiding catheter into the patient""s coronary vasculature until the distal end of the guide wire crosses the arterial location where the interventional procedure is to be performed, e.g. a lesion to be dilated or a dilated region where a stent is to be deployed. The catheter, which is slidably mounted onto the guide wire, is advanced out of the guiding catheter into the patient""s coronary anatomy by sliding over the previously introduced guide wire until the operative portion of the intravascular device, e.g. the balloon of a dilatation or a stent delivery catheter, is properly positioned across the arterial location. Once the catheter is in position with the operative means located within the desired arterial location, the interventional procedure is performed.
With the bare wire technique, the guide wire is first advanced by itself through the guiding catheter until the distal tip of the guide wire extends beyond the arterial location where the procedure is to be performed. Then a rail type catheter, such as described in U.S. Pat. No. 5,061,395 (Yock) and the previously discussed McInnes et al. which are incorporated herein by reference, is mounted onto the proximal portion of the guide wire which extends out of the proximal end of the guiding catheter which is outside of the patient. The catheter is advanced over the guide wire, while the position of the guide wire is fixed, until the operative means on the rail type catheter is disposed within the arterial location where the procedure is to be performed. After the procedure the intravascular device may be withdrawn from the patient over the guide wire or the guide wire repositioned within the coronary anatomy for an additional procedure.
Further details of guide wires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.): U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are hereby incorporated herein in their entirety by reference thereto.
Conventional guide wires for angioplasty, stent delivery, atherectomy and other vascular procedures usually comprise an elongate core member with one or more tapered sections near the distal end thereof and a flexible body member such as a helical coil or a tubular body of polymeric material disposed about the distal portion of the core member. A shapeable member, which may be the distal extremity of the core member or a separate shapeable ribbon which is secured to the distal extremity of the core member extends through the flexible body and is secured to the distal end of the flexible body by soldering, brazing or welding which forms a rounded distal tip. Torquing means are provided on the proximal end of the core member to rotate, and thereby steer, the guide wire while it is being advanced through a patient""s vascular system.
A problem confronting designers of successful guide wires is the desirability to provide different physical characteristics for different parts of the guide wire. For example, many guide wires have a highly flexible leading tip designed not to damage or perforate the vessel. Further, the portion behind the distal tip is increasingly stiff to better support a balloon catheter or similar device. The more proximal portion of the guide wire must also have sufficient torsional rigidity to allow the tip to be steered through the coronary vasculature.
One solution that has been employed is to provide a guide wire having a core member with tapered diameters as discussed above. However, it can be difficult to obtain the desired handling characteristics on the basis of core wire dimensions alone. Other solutions have involved the use of different materials for different portions of the guide wire. These attempts raise new problems in obtaining appropriately secure connections between the different materials while maintaining the desired low profile. Further, it can be important to provide a smooth transition between regions of different stiffness in a guide wire to minimize the potential of kinking.
It is also desirable to provide a guide wire with a lubricious coating to facilitate advancement of the guide wire through the tortuous coronary vasculature. However, placing suitable coatings on metal guide wires raises significant manufacturing problems. Typically, the metal surface must be pretreated to allow adhesion of the lubricious coating. This adds to the expense and difficulty of producing. guide wires. The present invention solves these and other problems.
This invention is directed to an elongate intraluminal device having an elongate core member with a proximal portion, an intermediate portion and a distal portion with a first polymeric jacket and a second polymeric jacket disposed about the core member. In a preferred embodiment, the first polymeric jacket is disposed about the intermediate portion of the elongate core and the second polymeric jacket is disposed about the distal portion of the core. Preferably, the intraluminal device is a guidewire and the first polymeric jacket is composed of a different polymer than the second polymeric jacket, or the first polymeric jacket has different polymeric properties than the second polymeric jacket. The use of different polymers or polymer properties imparts different handling characteristics to the various portions of the guide wire. Preferably, the first polymeric jacket is harder or has a higher shore hardness than the second polymeric jacket so that the distal portion of the guide wire is more flexible than the intermediate portion.
The polymeric jackets may comprise any suitable polymers such as polyurethanes or fluoropolymers. In one preferred embodiment, the first jacket comprises polyurethane having a shore hardness of up to about 70D, preferably about 50D to about 60D. The second jacket is generally is of a softer or more flexible material than the first jacket. Typically a polyurethane having a shore hardness of about 75A to about 100A, preferably about 85A to about 95A is used for the second jacket. In a typical embodiment, a first jacket of shore hardness 55D is used with a second jacket having a durometer of 90A. While the use of two discrete polymer jackets is preferred, the invention is also directed to the use of three or more polymer jackets as well as a single polymer jacket having a continuously varying shore hardness over a longitudinal length of the single polymer jacket. In another preferred embodiment, the first jacket is made of polyurethane while the second jacket is made of a fluoropolymer. In embodiments where the guide wire has a shapeable coil at the distal tip, the second jacket should cover the coil.
The invention also includes a processes for making guide wires having multiple polymeric jackets or a jacket of continuously varying characteristics to impart differing handling characteristics to different portions of the guide wire. Preferably, the process involves jacketing the guide wire by hot die necking. In embodiments where the guide wire has a shapeable coil over a core member, it may be desirable to configure the process so that gaps between the turns of the coil and between the coil and the core member are filled with polymeric material to minimize any air voids.